In an existing long term evolution (LTE) system, an access network device in LTE accesses an evolved packet core network (EPC) through an Si interface, and in addition, access network devices are connected to each other through an X2 interface to exchange information. During smooth evolution from a 4G core network to a 5G core network, the LTE system may be evolved into an evolved LTE (eLTE) system, and therefore an access network device in eLTE has a function of accessing the 5G core network. In the embodiments of this application, the 5G core network that supports the new function is also referred to as a next-generation core network (NG-Core). On an air interface, the eLTE system still provides a service for a terminal in an LTE manner.
To use the new function enhanced in eLTE, in a deployment scenario in which eLTE and LTE coexist, the access network device in eLTE and the access network device in LTE use a same frequency and a same air interface technology, especially a same physical layer technology. However, in the foregoing scenario, currently, there is no effective solution for accessing an evolved long term evolution cell by the terminal.